Packaged dual phase mouthwash compositions having two visibly distinct layers, one on top of the other, are prone to suffering from problems with their cosmetic stability. In particular, such compositions have a tendency to develop a cloudy appearance over time, once the consumer has commenced use of a particular container of the mouthwash. Also, upon manufacture, the high-speed filling of the two layers into the mouthwash container tends to cause problems of increased opacity in the mouthwash composition. These problems of increased opacity can also arise during shipping of the product to retail outlets.
It would be desirable to provide mouthwash compositions having at least two layers disposed one on top of the other, in which the cosmetic acceptability of the composition is maintained over time, even once the consumer has started to use the particular container of mouthwash.